1. Technical Field
The present invention relates to a light source and a projector including the light source.
2. Related Art
A projector of a type which modulates light emitted from a light source to form an image and projects the formed image on a screen or the like is known. This projector includes a light source which has an arc tube and a reflector as a reflection mirror for reflecting light emitted from the arc tube. The arc tube has a light emitting portion containing a pair of electrodes, and sealing portions extending from both sides of the light emitting portion.
A light source having this structure in related art includes a cooling system which takes heat generation distribution of the arc tube into consideration so as to prevent loss of transparency and blacking and allow prolongation of life of the light source. For example, a technology currently proposed introduces cooling air into the light source and guides the introduced air toward the inside of the reflector by using a concave surface of a concave lens to cool an area around the arc tube (see JP-A-2005-70216). Another related-art cooling system has an air supply port on the reflector and guides air introduced through the air supply port from an area above the arc tube toward an area below the arc tube (see JP-A-2004-342599).
According to the technologies disclosed in JP-A-2005-70216 and JP-A-2004-342599, a flow path of cooling air to be introduced into the light source is formed such that the air passes the sealing members constituting the arc tube. However, there is a possibility that the air only cools a part of the arc tube depending on the structure of the flow path, resulting in non-uniform temperature distribution around the arc tube. In this case, the halogen cycle becomes inefficient, and thus loss of transparency or blacking of the arc tube is caused. Accordingly, these technologies are unsatisfactory as a cooling system. In addition, according to the cooling system disclosed in JP-A-2004-342599, the process of forming an opening on the reflector and producing the air supply port thereon is needed.
Furthermore, the technologies described above cannot provide an appropriate cooling condition inside the light source which is included in a projector suspended from the ceiling and installed upside down during use.